Capacitors, couplers, devices including same and methods of manufacturing same

ABSTRACT

Capacitors are provided comprising a first plate, a second plate spaced from the first plate and a dielectric between the first and second plates. In certain embodiments the plates are arranged generally opposite each other and each is shaped in a periodically repeating pattern that is spatially out of phase with the other so that misregistration of the plates is compensated. In certain embodiments, a floating equipotential conductor is positioned between the plates and has a larger dimension than a corresponding dimension of the plates so that misregistration of the plates is compensated. Methods of manufacturing the capacitors are also provided.

This application claims the benefit of U.S. provisional patentapplication No. 60/871,702, filed Dec. 22, 2006 in the names of HarveyJ. Horowitz and Bernard Horowitz.

Capacitors, couplers, devices including same and methods ofmanufacturing the foregoing are disclosed.

BACKGROUND

A wide variety of electronic devices are manufactured using processesthat involve the placement or formation of device structures in apredetermined relationship to one another within close tolerances. Amongsuch devices are capacitors, couplers and devices including one or moreof these devices, in which two or more conductors must be placed orformed in close alignment in order to produce a device havingpredetermined electrical characteristics within a range of acceptabletolerances. Those devices that fail to exhibit such characteristicswithin such tolerance range must be discarded. The greater theproportion of unacceptable to acceptable devices, the more expensive theacceptable devices become, and the lower the manufacturer's gross profiton the sale of the devices.

As an example, coupled transmission lines and hybrid couplers have beenimplemented by two elongated rectangular metal plates having the samedimensions and separated by a dielectric layer. The goal of themanufacturing process for producing such devices is to align the platesas closely as possible both in their longitudinal and lateral directionsto provide a capacitance as close as possible to design parameters.However, due to mis-registration of the masks or other devices used toform or position the plates, they can become misaligned in both in thelongitudinal and lateral directions. Such misalignment results in adeviation of the capacitance of the capacitor formed by the opposingplates, which can exceed the design tolerance, resulting in rejection ofthe device.

DISCLOSURE

Various features and aspects of the capacitors, couplers, devices andmethods are disclosed below in conjunction with the accompanyingdrawings, in which:

FIG. 1 is a three-dimensional view illustrating an embodiment of acapacitor having plates structured to reduce sensitivity of the device'scapacitance to misalignment of the plates;

FIGS. 1A and 1B are used to illustrate the reduced sensitivity of the

FIGS. 2A, 2B and 2C illustrate a process for manufacturing the capacitorof FIG. 1;

FIG. 3 is a three-dimensional view illustrating a further embodiment ofa capacitor having plates structured to reduce sensitivity of thedevice's capacitance to misalignment of the plates;

FIGS. 3A and 3B are used to illustrate the reduced sensitivity of thecapacitor of FIG. 3 to misalignment of its plates;

FIG. 4 is a partially broken away, three dimensional view of a capacitorstructure of a further embodiment providing reduced sensitivity tomisalignment of its plates;

FIG. 4A is a cross-sectional view of the FIG. 4 embodiment;

FIG. 4B is a further version of the embodiment of FIG. 4;

FIG. 4C is a partial, three-dimensional view of a capacitor structuresimilar to those of FIGS. 4, 4A and 4B, having advantageously arrangedconnectors;

FIG. 5 is a schematic representation of a transmission line comprisingany of the embodiments of FIGS. 1, 3, 4, 4B and 4C; and

FIG. 6 is a schematic representation of a balanced amplifier making useof hybrid couplers comprising any of the embodiments of FIGS. 1, 3, 4,4B and 4C.

With reference to FIG. 1, a capacitor 20 comprises an upper plate 30 anda lower plate 40 separated from the upper plate 30 by a dielectric (notshown for purposes of simplicity and clarity in FIG. 1). In certainembodiments, the dielectric comprises a gas, such as air, or a liquid,such as oil, or a vacuum. In certain embodiments in which the plates 30and 40 of capacitor 20 are formed on a substrate, the dielectricmaterial comprises a solid, such as glass, ceramic or polymer. Aconductor 42 extends from one end of plate 30, while a conductor 44extends from an end of plate 40 opposite the end of plate 30 from whichconductor 42 extends. Conductors 42 and 44 provide leads for formingconnections with the plates 30 and 40.

It will be seen from FIG. 1 that plates 30 and 40 extend longitudinallyin a direction 50 and in a lateral direction 60 perpendicular to thelongitudinal direction 50 and are generally aligned in a verticaldirection, as indicated by dashed lines 66. It will also be seen thatupper plate 30 comprises a plurality of generally rectangular sections70, 72, 74, 76, 78, 80, 82 and 84 longitudinally displaced from eachother and arranged in sequence along the longitudinal direction 50,while lower plate 40 comprises a plurality of generally rectangularsections 90, 92, 94, 96, 98, 100, 102 and 104 longitudinally displacedfrom each other and extending in sequence along the longitudinaldirection 50. In this embodiment, each of the generally rectangularsections 70, 72, 74, 76, 78, 80, 82 and 84 is displaced in the lateraldirection from each adjacent one of such sections of upper plate 30,while each of the generally rectangular sections 90, 92, 94, 96, 98,100, 102 and 104 is displaced in the lateral direction from eachadjacent one of such sections of lower plate 40. It will also beappreciated that the pattern of the rectangular sections of upper plate30 is generally symmetrical, as is that of the rectangular sections oflower plate 40, and that each such pattern is defined by a periodicwaveform extending along the longitudinal direction 50, such that eachrectangular section has the same length and width. The waveform definingthe patterns of the rectangular sections of the upper and lower plates30 and 40 of FIG. 1 is a square wave, although it will be seen that thepatterns of other embodiments of capacitors and couplers are defined bysinusoidal waveforms, linear combinations of sinusoidal waveforms,triangular waveforms and/or ramps. In general, any periodic pattern maybe employed.

It is also evident from FIG. 1 that the waveform defining the pattern ofupper plate 30 is offset from the waveform defining the pattern of lowerplate 40 by approximately π radians. It will be seen, as explained belowin connection with FIGS. 1A and 1B, that misalignment of the plates 30and 40 in either or both of the directions 50 and 60, within limits,results in very little change in the total area by which plates 30 and40 overlap. Since, in general, the capacitance formed by plates 30 and40 is dominated by the parallel plate capacitance which is proportionalto the overlapping area between the plates 30 and 40, misalignment ofthe plates, within limits, has an advantageously minor effect on theoverall capacitance formed by plates 30 and 40 of the FIG. 1 embodiment.

FIG. 1A illustrates the case in where plates 30 and 40 are aligned bothin the direction 60 and the direction 50, so that the periodic patternsformed by areas 74, 76, et al., of plate 30 are π radians out of phasewith the periodic pattern formed by areas 94, 96, et al. of plate 40. Inthis case the total overlapping area of the plates within an extent of2π radians along direction 50 can be represented by the dimensionsillustrated in FIG. 1A as follows: (w−2a)(|)=w(|)−2a(|).

FIG. 1B illustrates the case where the plates 30 and 40 are offset by dxin the direction 50 and by dy in the direction 60. Here, the totaloverlapping area within an extent of 2π radians along direction 50 canbe expressed as the sum of six sub-areas: (1) two sub-areas 120, 124,each equal to (2a−dy)(dx), (2) two sub-areas 130, 134, each equal to(w−2a)(dx), (3) a sub-area 140 equal to (w−2a+dy)(|/2−dx), and(w−2a−dy)(|/2−dx). The sum of all six areas may be expressed as(w−2a)(|)+4a(dx)−2(dy)(dx).

As an example, where the plates 30 and 40 are correctly aligned as shownin FIG. 1A, it is assumed that the dimensions shown in FIG. 1A are asfollows: w=20 mils, a=4 mils, and |=100 mils. In this case, theoverlapping area of a portion of the structure extending for 2π radiansin the direction 50, is (w−2a)(|)=(20−2*4) * 100 mils²=1200 mils². If,however, the plates 30 and 40 are misaligned so that dx=1 mil and dy=1mil, the overlapping area becomes (w−2a)(|)+4a(dx)−2(dx)(dy)=[(20−2*4)(100)+(4*4*1)−(2*1*1)] mils²=1214 mils². Thus, amisregistration of plates 30 and 40 of 1 mil in the direction 50 (thelongitudinal direction) and 1 mil in the direction 60 (the lateraldirection), results in a change of 1214/1200, or 1.17 percent in theoverlapping area.

In a contrasting example, two rectangular plates are used in place ofplates 30 and 40, each of the rectangular plates having a section 12mils wide by 100 mils long to form the same overlapping area as the 2πradian-long portion of the FIG. 1 embodiment, that is, 1200 mils², whenprecisely aligned. If, however, the rectangular plates are misaligned tothe same extent as plates 30 and 40 of the FIG. 1B example, that is, by1 mil in the longitudinal direction and 1 mil in the lateral direction,the overlapping area becomes (11 mils)(99 mils)=1089 mils². Thus, amis-registration of the two rectangular plates of | mil in thelongitudinal direction and 1 mil in the lateral direction results in achange of 1089/1200, or 9.25 percent in the overlapping area, which is9.25/1.17=7.9 times worse than the embodiment of FIG. 1 when misalignedto the same extent.

Thus, the capacitor structure of FIG. 1 substantially alleviates theproblem of misalignment encountered in prior art devices, resulting insubstantially higher manufacturing yields for capacitors and devicesthat incorporate them. The capacitor structure of FIG. 1 is particularlyuseful at lower frequencies where the abrupt changes along theperipheries of the plates 30 and 40 do not induce non-TEM modes in thestructure which could adversely affect its useful properties. Typically,the periodicity should be less than about 5 percent of the shortestwavelength at which the structure will be used, although largerperiodicities can be employed depending on the required parameters.

A capacitor comprises a first plate extending longitudinally in a firstdirection and in a second direction perpendicular to the firstdirection; a second plate extending longitudinally in the firstdirection and in the second direction perpendicular to the firstdirection; at least a portion of the first plate being arranged oppositeat least a portion of the second plate; and a dielectric separating thefirst plate from the second plate; the first plate having at least onefirst portion and at least one second portion displaced longitudinallyfrom the at least one first portion, the at least one portion of thefirst plate being displaced in the second direction relative to the atleast one second portion of the first plate; the second plate having atleast one first portion and at least one second portion displacedlongitudinally from the at least one first portion, the at least oneportion of the second plate being displaced in the second directionrelative to the at least one second portion of the second plate; thefirst portion of the first plate being aligned longitudinally at leastpartially with the first portion of the second plate to define a firstopposing area; the second portion of the first plate being alignedlongitudinally at least partially with the second portion of the secondplate to define a second opposing area; the first portions of the firstand second plates being displaced in the second direction from eachother and the second portions of the first and second plates beingdisplaced in the second direction from each other.

A capacitor comprises a first plate extending longitudinally in a firstdirection and in a second direction perpendicular to the firstdirection; a second plate extending longitudinally in the firstdirection and in the second direction perpendicular to the firstdirection; at least a portion of the first plate being arranged oppositeat least a portion of the second plate; and a dielectric separating thefirst plate from the second plate; the first plate and the second plateeach having first longitudinally extending portions displaced laterallyand longitudinally from second longitudinally extending portions thereofsuch that the first and second longitudinally extending portions form aperiodic pattern of laterally displaced areas extending along thelongitudinal direction; the periodic pattern of the first longitudinallyextending portion being displaced by π radians from the periodic patternof the second longitudinally extending portion with or without a furtherlongitudinal displacement due to misalignment of the first and secondplates.

A capacitor comprises a first plate extending longitudinally in a firstdirection and in a second direction perpendicular to the firstdirection; a second plate extending longitudinally in the firstdirection and in the second direction perpendicular to the firstdirection; at least a portion of the first plate being arranged oppositeat least a portion of the second plate; and a dielectric separating thefirst plate from the second plate; each of the first and second platesbeing displaced in the second direction in a periodically repeatingpattern along an extent thereof in the first direction such that theperiodic patterns of the first and second plates have a phase differenceof substantially π radians along the first direction with or without afurther displacement in the first direction due to misalignment of thefirst and second plates.

An embodiment of a process for manufacturing the capacitor of FIG. 1 isillustrated in FIGS. 2A, 2B and 2C. With reference first to FIG. 2A, inthis particular embodiment, a dielectric substrate 200 has a surface 210on which the lower plate 40 is formed with the use of a mask (not shownfor purposes of simplicity and clarity) to define the shape of the lowerplate 40. Deposition of a conductive material (such as gold, copper,silver, aluminum, other conductor or a semiconductor) to form lowerplate 40 is carried out by physical vapor deposition, chemical vapordeposition, electrochemical deposition, evaporative deposition,sputtering, molecular beam epitaxi, or any other suitable process fordeposition of a conductor or semiconductor. In certain embodiments,after the conductive material has been formed as a layer over surface210, the desired shape of lower plate 30 is formed by chemical etching,plasma etching, ion beam milling, or other suitable subtractive process.In the alternative, lower plate 30 can be formed by any known additiveprocess.

As illustrated in FIG. 2B, after lower plate 40 has been formed onsurface 210, a layer 220 of dielectric material such as silicon dioxide,silicon nitride, ceramic or any other suitable dielectric, is formedover surface 210 by physical vapor deposition, chemical vapordeposition, electrochemical deposition, evaporative deposition,sputtering, molecular beam epitaxi, or any other suitable process fordeposition of a dielectric material, which is closely controlled toproduce a dielectric layer over lower plate 40 having a predeterminedthickness.

With reference to FIG. 2C, the upper plate 30 is formed on thedielectric layer 220 so that it is aligned with lower plate 40 as shownin FIG. 1. Upper plate 30 is formed in the same manner as lower plate 40or in a different manner by physical vapor deposition, chemical vapordeposition, electrochemical deposition, evaporative deposition,sputtering, molecular beam epitaxi, or any other suitable process fordeposition of a conductor or semiconductor. As in the case of lowerplate 30, upper plate 40 may be shaped by any suitable subtractiveprocess, or in the alternative upper plate 40 can be formed by any knownadditive process.

In certain embodiments, a further dielectric layer is formed over upperplate 30. In certain ones of such further embodiments, a conductiveground plane is formed over such further dielectric layer and serves toproduce a full stripline structure having very low dispersion. Incertain embodiments, a further conductive ground plane is formed on abottom surface of substrate 200 for the same purpose as the conductiveground plane that is formed over the further dielectric layer. Incertain alternative embodiments, the dielectric substrate 200 is formedon a conductive substrate that acts as a conductive ground plane.

A method of manufacturing a capacitor comprises placing or forming afirst plate in or on a dielectric substrate, the first plate extendinglongitudinally in a first direction in or on the dielectric substrateand in a second direction perpendicular to the first direction; placingor forming a dielectric material on the first plate; and placing orforming a second plate in or on the dielectric material, so that thesecond plate extends longitudinally in the first direction of thedielectric substrate and in the second direction perpendicular to thefirst direction, so that the second plate is separated from the firstplate by the dielectric material and at least a portion of the secondplate is arranged opposite at least a portion of the first plate; eachof the first and second plates being displaced in the second directionin a periodically repeating pattern along an extent thereof in the firstdirection such that the periodic patterns of the first and second plateshave a phase difference of substantially π radians along the firstdirection with or without a further displacement in the first directiondue to misalignment of the first and second plates.

FIG. 3 Illustrates a further embodiment of a capacitor 300 formed ofopposing plates, that is, an upper plate 310 and a lower plate 320separated from the upper plate 310 by a dielectric (not shown forpurposes of simplicity and clarity in FIG. 3). As in the case of theembodiment of FIG. 1, the dielectric comprises a gas, such as air; aliquid, such as oil; a solid, such as glass, ceramic or polymer, or avacuum. A conductor 312 extends from one end of plate 310 to provide anelectrical connection to plate 310, while a conductor 322 extends froman end of plate 320 to provide an electrical connection thereto. Incertain embodiments, connections are made to plates 310 and 320 atopposing ends thereof. In certain embodiments, connections are made toeach of plates 310 and 320 at both ends thereof.

In general, the plates 310 and 320 are aligned both in a longitudinaldirection 330 and in a lateral direction 340, so that at least a portionof upper plate 310 opposes lower plate 320. Each of plates 310 and 320is formed to have longitudinally extending portions that are bothlongitudinally and laterally displaced from at least one adjacent suchportion thereof. For example, plate 310 has a first longitudinallyextending portion 350 that is displaced laterally from a second portion352 thereof that is adjacent to first portion 350 but displacedtherefrom longitudinally, so that together first and second portions 350and 352 form a full cycle of a sinusoidal pattern of upper plate 310. Afurther cycle of such pattern is formed by longitudinally and laterallydisplaced, but adjacent portions 354 and 356, while a third is formed bylongitudinally and laterally displaced, but adjacent portions 358 and360.

Similarly, lower plate 320 has a first longitudinally extending portion364 adjacent to a second portion 366 both longitudinally and laterallydisplaced from portion 364, so that portions 364 and 366 together form afull cycle of a sinusoidal pattern of lower plate 320. Longitudinallyand laterally displaced, but adjacent portions 368 and 370 form afurther cycle of the sinusoidal pattern, while a third is formed bylongitudinally and laterally displaced, but adjacent portions 372 and374. In general, where plates 310 and 320 are in alignment orregistration, the sinusoidal patterns of plates 310 and 320 aredisplaced by one-half cycle, or π radians, in the longitudinaldirection, and the edges of plates 310 and 320 are aligned vertically ateach half cycle, as indicated by dashed lines 378 in FIG. 3. In certainembodiments, the capacitor 300 is manufactured in the manner describedabove in connection with FIGS. 2A through 2C, while in certainembodiments, capacitor 300 is manufactured using a differentmanufacturing process.

It will be seen, as explained below in connection with FIGS. 3A and 3B,that misalignment of the plates 310 and 320 in either or both of thedirections 330 and 340, within limits, results in very little change inthe total area by which plates 310 and 320 overlap. Since, in general,the capacitance formed by plates 310 and 320 is dominated by theparallel plate capacitance which is proportional to the overlapping areabetween the plates, their misalignment, within limits, has anadvantageously minor effect on the overall capacitance they form.

FIG. 3A schematically illustrates a procedure for calculating anoverlapping area formed by plates 310 and 320 in the case where theplates are in alignment, wherein the edges of plate 310 are representedby solid lines and those of plate 320 by dashed lines. It will be seenthat, because of the repeating sinusoidal pattern formed by plates 310and 320, to characterize it, it is sufficient to calculate theoverlapping area from 0 to 2π alone, which is cross-hatched in FIG. 3A.Within this interval, it will also be seen that the area is symmetricalabout the point (π, 0) so that the total overlapping area from 0 to 2πmay be obtained as: 4∫(y₁−a(sin θ)) dθ, evaluated for the interval 0 toπ, which is 4πy₁−8a.

FIG. 3B illustrates the case where the plates 310 and 320 are offset byφ radians in the longitudinal direction 330 and by dy in the lateraldirection 340. In this case, a different illustrative interval of 2πradians in the direction 330 is evaluated; however, due to thesymmetries of the patterns formed by plates 310 and 320, it isimmaterial which such interval is selected for this evaluation.

To simplify the calculation of the overlapping area, the area integralsare evaluated over intervals bounded by points where the edges of theplates 310 and 320 intersect in the vertical direction. Due to theoffset of φ radians in the longitudinal direction 330, it will be seenthat the edges of plates 310 and 320 intersect in the vertical directionat a position α radians before the origin (selected as the position θ=0in FIG. 3B). The upper edge of plate 310 corresponds to a curvey=y₁+a(sin θ); however, since plate 320 is offset by φ radians withrespect to plate 310, its upper edge corresponds to a curvey=y₁−dy−a(sin (θ−φ)). By setting the values of y for both curves equaland substituting α for θ, the value of α can be calculated.

To find the total overlapped area, the following integrals areevaluated, where the functions are identified in FIG. 3B: (1) ∫f₁dθ,over the interval (−α) to (π+φ+α); (2) ∫f₂dθ, over the same interval asf₁; (3) ∫f₃dθ, over the interval (π+φ+α) to (2π−α); and ∫f₄dθ, over thesame interval as f₃. When terms are combined, the total area isexpressed as 4y₁π−2dyφ−4dyα−4a(cos α)−4a(cos (φ+α).

As an example, if it is assumed that the width of each plate 310 and 320is 20 mils, so that y₁=10 mils; that the sine amplitude a=4 mils; andthat the period of the sinusoidal pattern is 100 mils, so that π radianscorresponds to 50 mils, where the plates 310 and 320 are in alignment asin FIG. 3A, the overlapping area=4y₁π−8a=(4)(10)(50)−(8)(4)=1968 mils².To assess the sensitivity of the FIG. 3 embodiment to misalignment, alateral offset dy between the plates of 1 mil and a longitudinal offsetof 1 mil are introduced into this example. Since the period of thesinusoidal pattern is 100 mils, φ=( 1/100)(360 degrees)=3.6 degrees, andfrom this value, along with the values of a and dy, the value of α isfound to be approximately 5.4 degrees, or about 1.5 mils. Applying theformula for calculating the overlapping area illustrated in FIG. 3B, asset out above, such area is found to be approximately 1972 mils². Thus,a misregistration of plates 310 and 320 of 1 mil in the direction 330(the longitudinal direction) and 1 mil in the direction 340 (the lateraldirection), results in a change of 1972/1968, or about 0.217 percent inthe overlapping area.

In a contrasting example, two rectangular plates are used in place ofplates 310 and 320, each of the rectangular plates having a section 20mils wide by 100 mils long to form an overlapping area of 2000 mils²when precisely aligned. If, however, the rectangular plates aremisaligned to the same extent as plates 310 and 320 of FIG. 3B, that is,by 1 mil in the longitudinal direction and 1 mil in the lateraldirection, the overlapping area becomes (19 mils)(99 mils)=1881 mils².Thus, a misregistration of the two rectangular plates of 1 mil in thelongitudinal direction and 1 mil in the lateral direction results in achange of 1881/2000, or 5.95 percent in the overlapping area, which is5.95/0.217 or about 27 times worse than the embodiment of FIG. 3.

FIG. 4 illustrates a further advantageous embodiment of a capacitor 400comprising first and second plates 410 and 420, respectively, embeddedin a dielectric matrix 430, with a floating equipotential conductor 440also embedded in the dielectric matrix 430 between plates 410 and 420.Plates 410 and 420, as well as conductor 440, each extends in alongitudinal direction 450 and in a lateral direction 460, and eachthereof is electrically isolated from the others by the dielectricmaterial of the matrix 430. Each of plates 410 and 420 and conductor 440is generally aligned with the others thereof in the longitudinaldirection 450 and in the lateral direction 460. A first ground plate 470is positioned on a top surface of dielectric matrix 430, while a secondground plate 480 is positioned on a bottom surface of dielectric matrix430. A conductive lead, pattern, pad or connector (not shown forpurposes of simplicity and clarity) is connected to each of the plates410 and 420 for connecting the same to other elements, circuits or thelike.

With reference also to FIG. 4A, which is a cross-sectional view ofcapacitor 400 along the lines 4A-4A in FIG. 4, it will be seen thatfloating equipotential conductor 440 has a larger lateral dimension orgreater width than either plate 410 or plate 420. Consequently, amisalignment of the plates 410 and 420 in the lateral direction 460(indicated in FIG. 4A as LD), within limits, will not materially affectthe value of the capacitance formed by the structure of capacitor 400,since plates 410 and 420 are shielded from one another by conductor 440.It will also be seen from the disclosure hereof that a misalignment ofconductor 440 with either or both of plates 410 and 420, within limits,will not materially affect such capacitance value.

In certain embodiments, floating equipotential conductor 440 has agreater longitudinal dimension than either of plate 410 or plate 420.Although not shown for purposes of simplicity and clarity, in suchembodiments, longitudinal midpoints of plates 410 and 420 are alignedgenerally with a longitudinal midpoint of conductor 440. Thus, anylongitudinal misalignment of plate 410 or 420 with respect to conductor440 or of conductor 440 with respect to either or both of plates 410 and420, will not, within limits, materially affect the capacitance ofcapacitor 400.

In certain embodiments, plates 410 and 420 have a generally rectangularconfiguration in the longitudinal and lateral directions 450 and 460. Incertain embodiments, plates 410 and 420 are configured as in FIG. 1 orin FIG. 3, or configured according to a different periodic pattern alongthe longitudinal directions thereof.

FIG. 4B is a cross-sectional view of a modified version of the FIG. 4embodiment taken in the same direction as the cross-sectional view ofFIG. 4A, in which elements in common with the FIG. 4 embodiment have thesame reference numerals. In the embodiment of FIG. 4B, additionalfloating equipotential conductors 490 and 492 are embedded in dielectricmatrix 430. Conductor 490 has the same dimensions as conductor 440 andis vertically aligned therewith above plate 410 and separated andelectrically isolated therefrom by the dielectric material of matrix430. Conductor 492 also has the same dimensions as conductor 440 and isvertically aligned therewith below plate 420 and separated andelectrically isolated therefrom by the dielectric material of matrix430. The embodiment of FIG. 4B provides very tight coupling inapplications such as hybrid couplers. Preferably, floating equipotentialconductors 440, 490 and 492 are connected to each other.

FIG. 4C illustrates a capacitor 402 similar to capacitors 400 and 400′having an upper plate 412 and a lower plate 422 separated by a floatingequipotential conductor 442 electrically isolated from plates 412 and422 by a dielectric (not shown for purposes of simplicity and clarity).Upper plate 412 has a first connector 413 at a first longitudinal endthereof and a second connector 414 at a second longitudinal end thereof.First connector 413 extends laterally from upper plate 412 in a firstlateral direction, while second connector 414 extends laterally fromupper plate 412 in a second lateral direction opposite the first lateraldirection.

Similarly, lower plate 422 has a third connector 423 at a firstlongitudinal end thereof proximate the first longitudinal end of upperplate 412 and a fourth connector 424 at a second longitudinal endthereof proximate the second longitudinal end of upper plate 412. Thirdconnector 423 extends laterally from lower plate 422 in the secondlateral direction, and so extends in a direction opposite the directionin which first connector 413 extends from upper plate 412. Fourthconnector 424 extends laterally from lower plate 422 in the firstlateral direction, and so extends in a direction opposite the directionin which second connector 414 extends from upper plate 412.

First connector 413 has a width (measured in the longitudinal directionof upper plate 412) which is substantially the same as a width of secondconnector 414 (also measured in the longitudinal direction of upperplate 412). Accordingly, a lateral displacement of upper plate 412,within limits, will not change the area by which upper plate 412overlaps the floating equipotential conductor 442, so that thecapacitance formed between upper plate 412 and conductor 442 issubstantially unaffected by such lateral displacement. It will also beseen from FIG. 4C that floating equipotential conductor 442 has a longerdimension in the longitudinal direction than upper plate 412 which ispositioned longitudinally between longitudinal ends of conductor 442.Accordingly, a longitudinal displacement of upper plate 412, withinlimits, will not substantially affect the capacitance formed by upperplate 412 and floating equipotential conductor 442.

Third connector 423 has a width (measured in the longitudinal directionof lower plate 422) which is substantially the same as a width of fourthconnector 424 (also measured in the longitudinal direction of lowerplate 422). Accordingly, a lateral displacement of lower plate 422,within limits, will not change the area by which lower plate 422overlaps the floating equipotential conductor 442, so that thecapacitance formed between lower plate 422 and conductor 442 issubstantially unaffected by such lateral displacement. It will also beseen from FIG. 4C that floating equipotential conductor 442 has a longerdimension in the longitudinal direction than lower plate 422 which ispositioned longitudinally between longitudinal ends of conductor 442.Accordingly, a longitudinal displacement of lower plate 422, withinlimits, will not substantially affect the capacitance formed by lowerplate 422 and floating equipotential conductor 442.

Moreover, it will be seen that, although the first and third connectors413 and 423, respectively, are located proximate to the samelongitudinal end of the structure of FIG. 4C, first connector 413 andthird connector 423 extend in opposite directions from the upper plate412 and the lower plate 422, respectively. In addition, it will also beseen that, although the second and fourth connectors 414 and 424,respectively, are located proximate to the same longitudinal end of thestructure of FIG. 4C, second connector 414 and fourth connector 424extend in opposite directions from the upper plate 412 and the lowerplate 422, respectively. Consequently, the structure of FIG. 4C ensuresthat substantially the only coupling between upper plate 412 and lowerplate 422 occurs within the area defined by the floating equipotentialconductor 442. The structure of FIG. 4C, when used as a hybrid couplerthus affords advantageously high reverse isolation.

In certain embodiments, the capacitors 400 and 400′ are manufacturedusing the techniques described above in connection with FIGS. 2A through2C, while in certain embodiments, capacitors 400 and 400′ aremanufactured using a different manufacturing process.

A capacitor comprises a first plate extending longitudinally in a firstdirection and in a second direction perpendicular to the firstdirection; a second plate extending longitudinally in the firstdirection and in the second direction perpendicular to the firstdirection; at least a portion of the first plate being arranged oppositeat least a portion of the second plate; a dielectric separating thefirst plate from the second plate; and a floating equipotentialconductor positioned between the first and second plates and having adimension in the second direction exceeding dimensions of the first andsecond plates in the second direction. In certain embodiments, thefloating equipotential conductor has a dimension in the first directionexceeding dimensions of the first and second plates in the firstdirection.

FIG. 5 schematically illustrates an application of any of the structures20, 300, 400, 400′ and 402 of FIGS. 1, 3, 4, 4B and 4C as a broadsidecoupled transmission line 500 comprising a first input connector 510connected to a first end of plate 30, 310, 410 or 412, as the case maybe, and a second input connector 520 connected to a first end of plate40, 320, 420 or 422 as appropriate. Transmission line 500 also comprisesa first output connector 530 connected to a second end of plate 30, 310,410 or 412, as the case may be, and a second output connector 540connected to a second end of plate 30, 310, 410 or 412 as appropriate.

The structures 20, 300, 400, 400′ and 402 of FIGS. 1, 3, 4, 4B and 4Cfind applications at microwave frequencies in hybrids, directionalcouplers, filters, attenuators, baluns, and phase shifters. Anembodiment of a balanced amplifier 600 comprising any of such structuresused as a hybrid coupler is illustrated schematically in FIG. 6 in whicha first such hybrid coupler is indicated as 505 and a second as 506. Aninput of the balanced amplifier 600 is connected to port 1 of hybridcoupler 505, while port 2 of hybrid coupler 505, as the direct ortransmitted port, is connected to an input of an amplifier 640. Port 3of hybrid coupler 505, as the coupled port, is connected to an input ofan amplifier 630, while port 4 of hybrid coupler 505 is connected to afirst terminal of a 50Q termination resistor 650, whose second terminalis connected to ground.

Port 1 of hybrid coupler 506 is connected to an output of amplifier 630,while port 2 of hybrid coupler 506 supplies the output of the balancedamplifier 600. Port 3 of hybrid coupler 506 is connected to a firstterminal of a 50Ω termination resistor 660, whose second terminal isconnected to ground, while port 4 of hybrid coupler 506 is connected toan output of amplifier 640.

The structures of FIGS. 1, 3, 4, 4B and 4C are particularly useful indevices, such as balanced amplifier 600 of FIG. 6, which require verytight electrical coupling between the coupled lines of the capacitorstructures. However, devices that provide such tight coupling are verysensitive to a plate misalignment in the capacitor structure resultingin a deviation of the capacitance value from the design value. Thecapacitor structures of FIGS. 1, 3, 4, 4B and 4C substantially reducethe dependence of the capacitance value on the alignment of the plates,so that misalignment thereof, within limits, will improve themanufacturing yield for devices of this kind.

Although various embodiments of the present invention have beendescribed with reference to a particular arrangement of parts, featuresand the like, these are not intended to exhaust all possiblearrangements or features, and indeed many other embodiments,modifications and variations will be ascertainable to those of skill inthe art.

1. A capacitor, comprising: a first plate extending longitudinally in afirst direction and in a second direction perpendicular to the firstdirection; a second plate extending longitudinally in the firstdirection and in the second direction perpendicular to the firstdirection; at least a portion of the first plate being arranged oppositeat least a portion of the second plate; and a dielectric separating thefirst plate from the second plate; the first plate having at least onefirst portion and at least one second portion displaced longitudinallyfrom the at least one first portion, the at least one portion of thefirst plate being displaced in the second direction relative to the atleast one second portion of the first plate; the second plate having atleast one first portion and at least one second portion displacedlongitudinally from the at least one first portion, the at least oneportion of the second plate being displaced in the second directionrelative to the at least one second portion of the second plate; thefirst portion of the first plate being aligned longitudinally at leastpartially with the first portion of the second plate to define a firstopposing area; the second portion of the first plate being alignedlongitudinally at least partially with the second portion of the secondplate to define a second opposing area; the first portions of the firstand second plates being displaced in the second direction from eachother and the second portions of the first and second plates beingdisplaced in the second direction from each other.
 2. A capacitor,comprising: a first plate extending longitudinally in a first directionand in a second direction perpendicular to the first direction; a secondplate extending longitudinally in the first direction and in the seconddirection perpendicular to the first direction; at least a portion ofthe first plate being arranged opposite at least a portion of the secondplate; and a dielectric separating the first plate from the secondplate; the first plate and the second plate each having firstlongitudinally extending portions displaced laterally and longitudinallyfrom second longitudinally extending portions thereof such that thefirst and second longitudinally extending portions form a periodicpattern of laterally displaced areas extending along the longitudinaldirection; the periodic pattern of the first longitudinally extendingportion being displaced by π radians from the periodic pattern of thesecond longitudinally extending portion with or without a furtherlongitudinal displacement due to misalignment of the first and secondplates.
 3. A capacitor, comprising: a first plate extendinglongitudinally in a first direction and in a second directionperpendicular to the first direction; a second plate extendinglongitudinally in the first direction and in the second directionperpendicular to the first direction; at least a portion of the firstplate being arranged opposite at least a portion of the second plate;and a dielectric separating the first plate from the second plate; eachof the first and second plates being displaced in the second directionin a periodically repeating pattern along an extent thereof in the firstdirection such that the periodic patterns of the first and second plateshave a phase difference of substantially π radians along the firstdirection with or without a further displacement in the first directiondue to misalignment of the first and second plates.
 4. A method ofmanufacturing a capacitor, comprising: placing or forming a first platein or on a dielectric substrate, the first plate extendinglongitudinally in a first direction in or on the dielectric substrateand in a second direction perpendicular to the first direction; placingor forming a dielectric material on the first plate; and placing orforming a second plate in or on the dielectric material, so that thesecond plate extends longitudinally in the first direction of thedielectric substrate and in the second direction perpendicular to thefirst direction, so that the second plate is separated from the firstplate by the dielectric material and at least a portion of the secondplate is arranged opposite at least a portion of the first plate; eachof the first and second plates being displaced in the second directionin a periodically repeating pattern along an extent thereof in the firstdirection such that the periodic patterns of the first and second plateshave a phase difference of substantially π radians along the firstdirection with or without a further displacement in the first directiondue to misalignment of the first and second plates.
 5. A capacitor,comprising: a first plate extending longitudinally in a first directionand in a second direction perpendicular to the first direction; a secondplate extending longitudinally in the first direction and in the seconddirection perpendicular to the first direction; at least a portion ofthe first plate being arranged opposite at least a portion of the secondplate; a dielectric separating the first plate from the second plate;and a floating equipotential conductor positioned between the first andsecond plates and having a dimension in the second direction exceedingdimensions of the first and second plates in the second direction. 6.The capacitor of claim 5, wherein the floating equipotential conductorhas a dimension in the first direction exceeding dimensions of the firstand second plates in the first direction.